Radiant heater burner construction

ABSTRACT

An improved construction for the burner of a gas-fired, radiant heater in which a plurality of reverberator, combustion and guard grids are attached over the open face of a shaped plenum enclosure with common fasteners positioned around the periphery of and outside of the plenum. Between the grids and the fuel entrance to the plenum is a novel baffle plate secured within the plenum enclosure which acts to diffuse the fuel-air stream passing towards the grids and to thermally separate the rear of the plenum from the combustion area, thereby improving the directional heating characteristics of the device.

United States Patent [1 1 Karlovetz [111 3,814,573 1451 June 4,1974

[ RADIANT HEATER BURNER CONSTRUCTION [75] Inventor: Arthur Raymond Karlovetz,

Fremont, Ohio [73] Assignee: International Magna Corporation, Cleveland, Ohio [22] Filed: Dec. 27, 1971 [21] Appl. No.: 212,214

{52] US. Cl. 431/329 [51] Int. Cl. F236 13/14 [58] Field of Search 431/329; 239/553.3, 590.3

[56] References Cited UNITED STATES PATENTS 3,198,240 8/1965 Keith el al. 431/329 3,229,680 1/1966 Herbert et 111.. 431/329 3,310,098 3/1967 Hardison 431/329 3,326,265 6/1967 Paulin 431/329 3.401.000 9/1968 Spaonara et a1. 431/329 FOREIGN PATENTS OR APPLICATIONS 1,449,685 7/1966 France 431/329 703.256 2/1965 Canada ..431/329 Primary Examiner-Carroll B. Dority, Jr. Attorney, Agent. or FirmHenry K. Leonard 1 1 ABSTRACT An improved construction for the burner of a gasfired, radiant heater in which a plurality of reverberator, combustion and guard grids are attached over the open face of a shaped plenum enclosure with common fasteners positioned around the periphery of and outside of the plenum. Between the grids and the fuel entrance to the plenum is a novel baffle plate secured within the plenum enclosure which acts to diffuse the fuel-air stream passing towards the grids and to thermally separate the rear of the plenum from the combustion area,-thereby improving the directional heating characteristics of the device.

1 Claim, 5 Drawing Figures PATENTEDJUM 4:974 3.814573 SHEET 2 0F 2 INVENTOR: AR THUR RKARL a 1/5 TZ.

aaJk/ f @W ATTYS.

. 1 RADIANT HEATER BURNER CONSTRUCTION This invention relates to a burner construction for a radiant heater, such as a portable infra-red heater which burns fuel from a pressurized source. More specifically, the invention relates to an improved construction for the radiant heater burner which eliminates a number of manufacturing problems hereinbefore encountered in fabricating such burners and which provides superior heat transfer characteristics.

Radiant heaters, of the infra-red or catalytic type. are commonly used as portable space heaters for industrial or recreational use. They have become increasingly popular with campers and sportsmen due to the fact that, particularly in the case of infra-red heaters, they provide a maximum heat output and can be used safely in closed spaces, such as within tents or campers, because of the complete combustion of the fuel-air mixture and consequent lack of undesirable exhaust gases. While this invention is described with reference to a portable infra-red heater, it is to be understood that the principles of this invention can be utilized with other types of heaters and need not be limited to the portable type of heater described in the specific embodiment shown in the drawings and discussed below.

It is an object of this invention to provide an improved construction for a radiant heater burner which eliminates the necessity for bolts or separate frames with gaskets or other complex methods of attaching the various burner grids to the burner plenum enclosure in which also provides a burner design which is highly efficient in radiating heat.

It is another object of this invention to provide a construction for a radiant heater burner which includes a novel baffle plate positioned within the plenum chamber which is effective both to diffuse the flow of fuel-air as it proceeds towards the area of combustion and is also effective to radiate heat from the rear of the combustion area towards the open face of the burner, thereby increasing the efficiency of the unit.

Other objects and advantages of the invention will be apparent to those skilled in the art, with reference being made to the accompanying drawings in which:

FIG. 1 is a view in elevation of a complete infra-red type portable burner unit, showing the burner construction of this invention as it would be used with a bottled source of fuel, such as bottled propane with a fuel valve associated therewith;

FIG. 2 is a view in elevation of the front of the burner unit of FIG. 1;

FIG. 3 is an expanded view in perspective of the burner unit, showing the various elements which make up the unit;

FIG. 4 is a cross sectional view of a portion of the burner unit illustrating the method of attaching the baffle plate during the construction thereof; and

FIG. 5 is a cross sectional view of the burner unit, showing its details of construction.

Referring first to FIG. 1, the burner unit, generally designated by reference numeral 10, is attached to a fuel supply pipe 11 which is threaded into a valve 12 secured to the top of the bottle fuel supply 13. The entire unit is supported by a stand 14 as shown, it being understood that various configurations of the stand can be used to position the unit as is most desirable for its intended use.

The metering valve 12 must be capable of precisely metering a given amount of fuel to the burner and can be of the type described in U.S. Pat. No. 2,868,224 or any other such valve commercially available. As it is well known to those skilled in the art. the liquid gas within the bottle. upon release from pressure and expansion within the various chambers of the valve 12, volatilizes and mixes with air which is drawn in through an air inlet 15 in the fuel line 11 as it passes towards the burner 10. When this fuel-air mixture reaches the burner 10, it is diffused and thoroughly mixed by the various members within the burner and finally is combusted or exploded at the combustion grid to thus create the source of radiant heat which is directed outwardly from the burner 10.

Referring to FIG. 3, the burner construction of this invention consists of a shaped plenum enclosure 16 which, in this embodiment, is shown to be a square, cup-like sheet metal stamping having a fuel entrance 17, better seen in FIG. 5, with a threaded flange '18 for attachment to the fuel line I l. The fuel entrance 1 7 can be at the back or on one side of the plenum closure. It should be understood that the principles of this construction can be used with any size of radiant burner, round, square, rectangular or other shape. The plenum enclosure 16 has a rear or bottom wall 19 and continuous side walls 20 which extend away from the rear wall to form the enclosure. The side walls 20 terminate in a continuous peripheral outer flange 21 whose surface is generally parallel to the rear or bottom wall 19 and which lies entirely outside of the plenum chamber. The outer edges of the flange 21 terminate in a lip 22 which extends around the entire periphery of the outer flange 21 and faces outwardly away from the bottom wall 19.

Within the plenum chamber is positioned a baffle plate 23 which is fixed within the plenum enclosure 16 behind the plane of the outer flange 21, as best seen in FIG. 5. Referring to FIG. 3, the baffle plate has one dimension which is substantially the same as the corresponding interior dimension of the plenum chamber and. a shorterdimension, designated as W in FIG. 3, which is less than the corresponding dimension of the plenum chamber so that, when thebaffle plate 23 is in position, a pair of elongate slots or passages for the fuel-air mixture to pass is provided. The baffle plate 23, has a pair of protrusions or tabs 24 on its opposed edges and the opposite side walls 20 of the plenum enclosure 16 are provided with inwardly extending channels 25 which are shaped to receive the tabs 24 on the baffle plate when it is moved inwardly into the plenum chamber as will be apparent from FIG. 3. The inner end of the channel 25 will determine the position of the baffle plate 23 within the plenum enclosure 16. The baffle plate 23 is attached to the plenum enclosure 16 by sliding it inwardly so that the tabs 24 slide within the channel 25 until reaching the end of the channels; at this position, as schematically shown in FIG. 4, the channel on the outer side of the bafile plate 23 is staked or otherwise collapsed to hold the baffle plate 23 in position.

Referring again to FIG. 3, a plurality of screen-like grids are secured over the opening of the plenum enclosure. 16 in the manner shown in FIG. 5. Depending upon the nature of the burner, the number and type of screens attached may vary. In this particular example, a primary screen comprising layers 26 and 27 and an outer reverberator grid 28 are used. The size of the primary screen layers 26 and 27 is such that they completely lie over the open face of the plenum enclosure 16 with their marginal edges overlapping the outer flange 21., as seen in FIGS. 2 and 5. ln this embodiment, the reverberator grid 28 is shaped so that its major surface 29 is spaced from the other grids by lateral-screen walls 30 which terminate in outwardly extending attachment flaps 31, the dimensions of which are such that the flaps 31 extend over the outer flange 21 on the plenum enclosure 16.

As seen in FIG. 5, with the baffle plate 23 installed as previously described, the grids 26, 27 and 28 are placed as shown against the outer flange 21 andare then attached in any suitable manner. Preferably, the

grids are attached by a plurality of staples 32 which can be easily applied through the grids 26, 27 and 28 and the flange 21. Other types of fasteners can be used or an extension of the lip 22 can be folded over on top of the screen, thus eliminating all bolts and gaskets. As shown in FIG. 5, the depth of the lip 22 is preferably at least as great or larger than the composite thickness of the grids placed on the flange 21 so that the edges of the grids, which may have sharp exposed wire ends, are completely covered by the lip 22.

As thus far described, the burner construction of this invention provides a means for the inexpensive fabricav tion of a burner having improved radiation characteristics. The baffle plate 23, in addition to causing diffusion of the fuel-air mixture as it emanates from the fuel entrance 17 into the plenum chamber, also serves to reflect radiation from the area of combustion forwardly to improve the directional characteristics of the burner. The relatively large grid area enabled by this construction also permits complete fuel-air diffusion and combustion with relatively low pressure build-up behind the grids. This means that there is less likelihood of leakage at the edges which therefore do not require any elaborate gaskets or other sealing means.

The method of mounting the primary screen and reverborator grid on the plenum enclosure 16 is advantageous in that it has no protruding or sharp edges which lie within the throat of the plenum chamber and thus become localized hot spots. None of the attaching means, such as the illustrated staples or folded peripheral edges, extend through the walls of the plenum enclosure 16 to cause a gas leakage problem; they all lie outside the path of fuel or gas flow. Finally, the lip 22 provides a mechanical guard for many of the sharp or hot edges of the grids and also will serve to channel any laterally outward radiation back towards the guard screen itself to improve the directional characteristics of the burner.

Other objects and advantages of this construction will be apparent to those skilled in the art and may be made without departing from the spirit and scope of th attached claims.

I claim:

l. A radiant heat generator comprising, in combination, a cup-shaped plenum enclosure having an open end, a fuel entrance into said enclosure which is spaced rearwardly from said open end, a peripheral'mounting flange extending around said open end, a primary screen comprising at least two contiguous layers of fine metal mesh extending across said open end and with the edge of the innermost one of said layers lying directly against said flange, a reverborator grid positioned over the open end of said enclosure, said reverborator grid having a generally planar body, return walls'at the edges of said body and outwardly extending edges on said return walls, the outer edges of said reverborator grid lying directly against the edges of the front one of said screen layers, means for securely retaining said screen and said grid against said mounting flange, and a baffle mounted generally parallel to said screen and within said enclosure between said fuel entrance and said screen, said baffle'extending substantially across said enclosure to define gas passages between the rear of said enclosure and the open end thereof, at least two opposed edges of said baffle having at least one extending tab, said plenum enclosure having shaped channels adapted to receive said tabs, said channels extending substantially normal to said baffle and screen whereby said baffle can be inserted within said plenum enclosure prior to mounting of said screen by sliding it normally into said open end, with the ends of said channels defining the distance of said baffle from said screen, 

1. A radiant heat generator comprising, in combination, a cupshaped plenum enclosure having an open end, a fuel entrance into said enclosure which is spaced rearwardly from said open end, a peripheral mounting flange extending around said open end, a primary screen comprising at least two contiguous layers of fine metal mesh extending across said open end and with the edge of the innermost one of said layers lying directly against said flange, a reverborator grid positioned over the open end of said enclosure, said reverborator grid having a generally planar body, return walls at the edges of said body and outwardly extending edges on said return walls, the outer edges of said reverborator grid lying directly against the edges of the front one of said screen layers, means for securely retaining said screen and said grid against said mounting flange, and a baffle mounted generally parallel to said screen and within said enclosure between said fuel entrance and said screen, said baffLe extending substantially across said enclosure to define gas passages between the rear of said enclosure and the open end thereof, at least two opposed edges of said baffle having at least one extending tab, said plenum enclosure having shaped channels adapted to receive said tabs, said channels extending substantially normal to said baffle and screen whereby said baffle can be inserted within said plenum enclosure prior to mounting of said screen by sliding it normally into said open end, with the ends of said channels defining the distance of said baffle from said screen. 